Push versus gravity for intermittent bolus gavage tube feeding of preterm and low birth weight infants

Abstract

Background

Many small, sick, and preterm infants are unable to co‐ordinate sucking, swallowing, and breathing, and therefore require gavage feeding. In gavage feeding, milk feeds are delivered through a tube passed via the nose or the mouth into the stomach. Intermittent bolus milk feeds may be administered by a syringe to gently push milk into the infant's stomach (push feed). Alternatively, milk can be poured into a syringe attached to the tube and allowed to drip in by gravity (gravity feed).

Objectives

To determine whether use of push feeding compared with gravity feeding results in more rapid establishment of full gavage feeds without increasing adverse events among preterm or low birth weight infants, or both, who require intermittent bolus tube feeding.

Search methods

We used the standard search strategy of Cochrane Neonatal to search the Cochrane Central Register of Controlled Trials (CENTRAL; 2020, Issue 7), in the Cochrane Library; Ovid MEDLINE(R) and Epub Ahead of Print, In‐Process & Other Non‐Indexed Citations, Daily and Versions(R); and the Cumulative Index to Nursing and Allied Health Literature (CINAHL), on 30 July 2020. We also searched clinical trials databases and the reference lists of retrieved articles for randomised controlled trials (RCTs) and quasi‐RCTs.

Selection criteria

We included RCTs and quasi‐RCTs comparing push versus gravity intermittent gavage tube feeding in preterm (less than 37 weeks' gestation) or low birth weight (less than 2500 grams) infants, or both.

Data collection and analysis

We assessed the methods of trials regarding blinding of randomisation and outcome measurement. We evaluated treatment effects with a fixed‐effect model using risk ratio (RR), relative risk reduction, risk difference (RD), and number needed to treat for an additional beneficial outcome (NNTB) for categorical data; and using mean, standard deviation, and mean difference (MD) for continuous data. We analysed outcomes measured as count data, for example, frequency of apnoea, bradycardia, and episodes of pulse oximeter oxygen (SpO₂) desaturation, by comparing rates of events and the rate ratio. We evaluated heterogeneity to help determine the suitability of pooling results. We used the GRADE approach to assess the certainty of evidence.

Main results

One small cross‐over trial (31 infants) met the criteria for inclusion in this review. The certainty of evidence for all outcomes was very low due to imprecision of estimates, wide confidence intervals, and unclear risk of bias.

The primary outcome ‐ time taken to establish full gavage feeding (days) and feeding intolerance (number of episodes per day) ‐ was not reported in the included study. The evidence is very uncertain about the effects of push versus gravity intermittent gavage tube feeding on all other outcomes.

Investigators reported respiratory rate (breaths per minute) at completion of feeding (MD 0.58, 95% confidence interval (CI) ‐5.97 to 7.13; 1 study, 31 participants; very low‐certainty evidence); respiratory rate (breaths per minute) 10 to 30 minutes after completion of feeding (MD 3.1, 95% CI ‐3.43 to 9.63; 1 study, 31 participants; very low‐certainty evidence); heart rate (beats per minute) at completion of feeding (MD 2.6, 95% CI ‐9.71 to 4.51; 1 study, 31 participants; very low‐certainty evidence); and heart rate (beats per minute) 10 to 30 minutes after completion of feeding (MD 2.4, 95% CI ‐9.16 to 4.36; 1 study, 31 participants; very low‐certainty evidence). We are very uncertain of the effects of push versus gravity intermittent gavage feeding on respiratory rate during and after feeding.

Authors' conclusions

We do not have sufficient evidence to determine the effects of intermittent bolus gavage feeding for preterm and low birth weight infants. The single small study of 31 infants comparing effects of push versus gravity bolus gavage feeding did not report the primary outcome identified in this review. Thus, evidence is insufficient to show whether use of push compared with gravity gavage feeding results in more rapid establishment of full gavage feeds without increasing adverse events in preterm or low birth weight infants who receive intermittent bolus gavage feeding. In addition, the included study was too small to measure potential adverse events that can occur during gavage tube feeding, for example, episodes of oxygen desaturation, apnoea, or bradycardia.

Plain language summary

Push versus gravity for intermittent bolus gavage tube feeding of preterm and low birth weight infants

Review question

In preterm or low birth weight infants receiving gavage tube feedings, does push tube feeding compared with gravity tube feeding result in increased adverse events (low oxygen saturation, low heart rate, time to full suck feeding). 

Background

Infants born prematurely (before 37 weeks) may be unable to co‐ordinate sucking, swallowing, and breathing, and require gavage feeding. In gavage feeding, milk is delivered intermittently through a tube passed via the nose or the mouth into the stomach. Intermittent bolus milk feeds may be administered by using a syringe to gently push milk into the infant's stomach (push feed). Alternatively, milk can be poured into a syringe attached to the tube and allowed to drip in by gravity (gravity feed).

Study characteristics

The search is up‐to‐date as of July 2020. We included one study (31 infants) in this updated review.

Key results

Evidence is insufficient to show whether use of push compared with gravity gavage feeding results in more rapid establishment of full gavage feeds without increasing adverse events in preterm or low birth weight infants, or both, who require intermittent bolus gavage feeding.

Certainty of evidence

Evidence from randomised trials comparing push versus gravity intermittent gavage tube feeding in preterm or low birth weight infants (less than 2500 grams) is insufficient to inform practice.

Summary of findings

Summary of findings 1. Summary of findings.

Push compared with gravity for bolus gavage feeding in preterm or low birth weight infants
Patient or population: intermittent bolus gavage tube feeding of preterm and low birth weight infants Settings: neonatal intensive care unit in the UK Intervention: push bolus gavage feeding Comparison: gravity bolus gavage feeding
Outcomes	Illustrative comparative risks* (95% CI)		Relative effect (95% CI)	No. of participants (studies)	Certainty of the evidence (GRADE)	Comments
	Assumed risk	Corresponding risk
	Gravity bolus gavage feeding	Push bolus gavage feeding
Time taken to establish full gavage feeding (days)			Not estimable	0	—	Included study did not examine this outcome
Feeding intolerance (number of episodes per day)			Not estimable	0	—	Included study did not examine this outcome
Respiratory rate (breaths per minute) at completion of feed	Mean (SD) respiratory rate in control group was 47.16 (11.91)	MD 0.58 higher (5.97 lower to 7.13 higher)		31 (1 study)	⊕⊝⊝⊝ Verylowa,b
Respiratory rate (breaths per minute) 10 to 30 minutes after completion of feed	Mean (SD) respiratory rate in control group was 47.93 (10.56)	MD 3.1 higher (3.43 lower to 9.63 higher)		31 (1 study)	⊕⊝⊝⊝ Very lowa,b
Heart rate (beats per minute) at completion of feed	Mean (SD) heart rate in control group was 151.4 (13.9)	MD 2.6 lower (9.71 lower to 4.51 higher)		31 (1 study)	⊕⊝⊝⊝ Verylowa,b
Heart rate (beats per minute) 10 to 30 minutes after completion of feed	Mean (SD) heart rate in control group was 155.5 (13.4)	MD 2.4 lower (9.16 lower to 4.36 higher)		31 (1 study)	⊕⊝⊝⊝ Verylowa,b
*The basis for the assumed risk (e.g. the median control group risk across studies) is provided in footnotes. The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). CI: confidence interval; MD: mean difference; SD: standard deviation.
GRADE Working Group grades of evidence. High certainty: further research is very unlikely to change our confidence in the estimate of effect. Moderate certainty: further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate. Low certainty: further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate. Very low certainty: we are very uncertain about the estimate.

^aDowngraded by two levels for imprecision because all data came from one small study and the wide confidence interval includes both benefit and harm.

^bDowngraded one level because measurement of respiratory rate and heart rate was not blinded to the intervention (risk of bias).

Background

Description of the condition

Many small, sick, and preterm infants are unable to co‐ordinate suck, swallow, and breathing (Pineda 2020), and require gavage feeding. In gavage feeding, milk feeds are delivered through a tube passed via the nose or the mouth into the stomach. Nutritional management influences immediate survival, as well as subsequent growth and development, of preterm and low birth weight infants (Lucas 1983; Mayerl 2019). Gavage feeding is commonly used when infants are unable to suck and swallow feeds due to prematurity, low birth weight, or other conditions. Gavage feeds can be given intermittently by push or gravity methods (Goswami 2017). Intermittent bolus feedings are considered to be more physiological than continuous feedings because they simulate a more normal feeding pattern and allow for cyclical surges in gut hormones (Aynsley‐Green 1990). Continuous gavage feedings are more commonly considered in very preterm infants with severe respiratory distress, or in infants who have shown previous intolerance of intermittent feedings as evidenced by severe reflux and/or persistent pre‐feed gastric residuals. However, a Cochrane Review has shown that small babies weighing less than 1500 grams who were fed by intermittent bolus (push or gravity) compared with continuous infusion showed no difference in the time needed to reach full feeds (Premji 2011). There was no subgroup analysis of the type of intermittent feeding ‐ push versus gravity ‐ in the included study.

The physiological effects of gavage feeding include a transient rise in postprandial oxygen consumption (Mukhtar 1982), as well as decreased oxygenation (Blondheim 1993; Hammerman 1995; Krauss 1978; Wilkinson 1974; Yu 1976), increased heart rate (Mukhtar 1982), decreased functional residual capacity (Heldt 1988), and decreased lung volumes (Pitcher‐Wilmott 1979). It is postulated that these cardiorespiratory effects are related to the volume displacement caused by feeds introduced into the stomach (Yu 1976). Additionally, intermittent bolus gastric tube feeding (gavage feeding) may decrease cerebral perfusion (Nelle 1997).

Description of the intervention

Gavage milk feeds may be delivered by intermittent bolus, by continuous drip, or by slow infusion over one hour, with an interval of at least one hour until the next feeding (Evans 2001). Intermittent bolus feeds can be given by push or by gravity. A 'push feed' is defined as an intermittent bolus milk feed that is administered by using a syringe to push milk into the infant's stomach. Alternatively, a 'gravity feed' is defined as an intermittent bolus milk feed by which milk is poured into a syringe (with the syringe used as a funnel) that is attached to an intragastric feeding tube, and the milk is allowed to drip into the infant's stomach by gravity (Stronati 1982). The flow of the milk feed is controlled by altering the height of the syringe. Lowering the syringe slows milk flow, and raising the syringe makes milk flow faster (Pagano 2010; Sankar 2008). A Cochrane Review has shown that small babies weighing less than 1500 grams who were fed by intermittent bolus (push or gravity) compared with continuous infusion showed no difference in time to achieve full oral feeds, nor in growth, days to discharge, or incidence of necrotising enterocolitis (Premji 2011).

How the intervention might work

The authors of two neonatal textbooks recommend that bolus gavage tube feeds should be given slowly, preferably by gravity (Townsend 1998; Wilkinson 1992). Sun 1998 strongly recommends against injecting fluid (milk) under pressure; similarly, Cox 1982 states, "feeding is never injected under pressure." The reasoning behind these authors' recommendations is not provided. Chinn 1971 argued that a preterm infant does not always have the “advantage of oesophageal peristalsis.” In addition, “stomach and intestinal peristalsis depend[s] on the presence of fluid in the stomach.” She reported that feeding by gravity stimulates the physiological response of peristalsis, as seen in the slight fluctuation of the formula level inside the syringe. Chinn 1971 asserted that the "forced‐syringe (push method) of gavage feeding is more likely to result in milk being given too rapidly." This in turn interferes with oesophageal peristalsis and results in oesophageal regurgitation (Barrie 1968; Haxhija 1998; Leidig 1989). In addition, fast gastric filling may lead to greater vagal stimulation resulting in bradycardia and apnoea, especially in low birth weight infants (Kindley 1980). Conversely, Ziemer 1978 argued that some pressure must be exerted, as gravity is generally insufficient for an entire feed to be administered. In an experimental laboratory study, Pagano 2010 reported that intermittent gravity feeding may result in an infant being fed a new feeding before the infant has digested the previous feeding if the feed is delivered slowly. Nurses who declare a preference for either method of intermittent gavage feeding claim that with their preferred method, they can more easily control the speed at which milk is delivered to the infant.

Why it is important to do this review

Since the 1960s, recommendations have been disparate and practice has been inconsistent regarding which method of intermittent bolus gavage tube feeding (push or gravity) is more efficacious in relation to establishment of full gavage feeding without adverse effects. The choice appears to be based primarily on personal preference, unit policy, or tradition. In a survey of neonatal units in the United Kingdom, the method of bolus feeding varied, with some units declaring a preference for push feeds and others preferring the gravity method of feeding (Symon 1994). We noted significant variation in gavage feeding while examining individual unit protocols published online. This variation in practice has been demonstrated in clinical studies using either the push method ‐ Barrie 1968; Grant 1991; Heldt 1988; Leidig 1989; Nelle 1997 ‐ or the gravity method ‐ Blondheim 1993; Greer 1984; Kindley 1980; Moscha 1995; Pagano 2010; Parker 1981 ‐ for bolus gavage feeding.

Because intermittent bolus gavage feeding is a common practice in neonatal intensive care and special care baby nurseries, it is important to determine the clinical risks and benefits of each method of feeding to enable clinicians to make informed decisions regarding the most appropriate feeding method for an individual infant. Therefore, this systematic review sought to include trials that compare the two methods of milk feeding.

Objectives

To determine whether use of push feeding compared with gravity feeding results in more rapid establishment of full gavage feeds without increasing adverse events among preterm or low birth weight infants, or both, who require intermittent bolus tube feeding.

Methods

Criteria for considering studies for this review

Types of studies

We considered all published and unpublished randomised controlled trials (RCTs) and quasi‐randomised trials eligible for inclusion in this review.

Types of participants

We included preterm infants (less than 37 weeks' gestation) or low birth weight infants (less than 2500 grams) who require partial or complete gavage tube feeding and have no congenital anomalies that might interfere with establishing enteral feeds.

Types of interventions

Push versus gravity gavage feeding.

Types of outcome measures

Primary and secondary outcomes.

Primary outcomes

1. Time taken to establish full gavage feeding (days)

2. Feeding intolerance (number of episodes per day): defined as significant abdominal distension or discolouration, signs of perforation, obvious blood in stool; gastric residuals ≥ 25% to 50% of interval volume for two to three feedings; bilious gastric residual or emesis; significant apnoea or bradycardia; significant cardiopulmonary instability (Kuzma‐O'Reilly 2003)

Secondary outcomes

All were to be assessed during gavage feeding. 

1. Apnoea during gavage feeding (frequency of episodes), defined as cessation of breathing for longer than 20 seconds or a shorter pause associated with bradycardia (< 100 beats per minute), cyanosis, or pallor (Eichenwald 2016).

2. Apnoea (frequency of episodes within 30 minutes following gavage feeding), defined as cessation of breathing for longer than 20 seconds or a shorter pause associated with bradycardia (< 100 beats per minute), cyanosis, or pallor (Eichenwald 2016).

3. Bradycardia during gavage feeding (frequency of episodes), defined as a fall in heart rate greater than 30% below baseline or less than 100 beats per minute for 10 seconds or longer.

4. Bradycardia (frequency of episodes within 30 minutes following gavage feeding), defined as a fall in heart rate greater than 30% below baseline or less than 100 beats per minute for 10 seconds or longer.

5. Spontaneous episode of oxygen desaturation during gavage feeding (frequency of episodes), defined as a spontaneous fall in oxygen saturation (SpO₂) of 85% or less for 10 seconds or longer.

6. Spontaneous episode of oxygen desaturation (frequency of episodes within 30 minutes following gavage feeding), defined as a spontaneous fall in SpO₂ of 85% or less for 10 seconds or longer.

7. Severe apnoea during gavage feeding (frequency of events), defined as cessation of breathing and a fall in heart rate greater than 30% below baseline or less than 100 beats per minute for 10 seconds or longer and a concurrent fall in SpO₂ of 85% or less.

8. Incidence of aspiration pneumonia (frequency of episodes).

9. Incidence of necrotising enterocolitis (Bell's stage II or greater) (including suspected and confirmed) (Bell 1978).

10. Days to regain birth weight.

11. Length of hospital stay (days) from admission to discharge.

Search methods for identification of studies

Electronic searches

We conducted a comprehensive update search including the Cochrane Central Register of Controlled Trials (CENTRAL; 2020, Issue 7), in the Cochrane Library; Ovid MEDLINE(R) and Epub Ahead of Print, In‐Process & Other Non‐Indexed Citations, Daily and Versions(R) (1 January 2012 to 30 July 2020); and the Cumulative Index to Nursing and Allied Health Literature (CINAHL) (1 January 2012 to 30 July 2020). We have included the search strategies for each database in Appendix 1. We did not apply language restrictions.

We searched clinical trial registries for ongoing and recently completed trials, including the US National Library of Medicine’s ClinicalTrials.gov (clinicaltrials.gov), via Cochrane CENTRAL. Additionally, we searched http://www.isrctn.com/, the Australian New Zealand Clinical Trials Registry (ANZCTR), the EU Clinical Trials Register (EU‐CTR), and the Clinical Trial Registry of India (CTRI) (the latter three from February 2020 onwards) for any unique trials not found through the Cochrane CENTRAL search.

This is the first update of a review originally published in 2012 (Dawson 2012). Our previous search details are listed in Appendix 2.

Searching other resources

We cross‐referenced relevant literature including identified trials and existing review articles to identify additional relevant articles.

Data collection and analysis

We used the standard methods of Cochrane Neonatal.

Selection of studies

We used Covidence to remove duplicates from search results sent by the Information Specialist. The review authors (JAD, RS, JPF) independently assessed study eligibility for inclusion in this review according to pre‐specified criteria. We listed excluded studies along with reason(s) for exclusion. We resolved any disagreement through discussion with another review author (JPF).

Data extraction and management

Two review authors (JAD, RS) separately extracted data. We resolved any differences by discussion with another review author (JPF). We requested additional information from the authors of trials to clarify methods and to seek further data, if necessary.

Assessment of risk of bias in included studies

Two review authors (JAD, JPF) independently assessed the risk of bias (low, high, or unclear) of all included trials using the Cochrane ‘Risk of bias’ tool (Higgins 2021), for the following domains.

1. Sequence generation (selection bias).

2. Allocation concealment (selection bias).

3. Blinding of participants and personnel (performance bias).

4. Blinding of outcome assessment (detection bias).

5. Incomplete outcome data (attrition bias).

6. Selective reporting (reporting bias).

7. Any other bias.

We resolved any disagreements by discussion or by consultation with a third assessor. See Appendix 3 for a more detailed description of risk of bias for each domain. 

Measures of treatment effect

Dichotomous variables were to be analysed using risk ratio and risk difference with 95% confidence intervals. We planned to report the number needed to treat for an additional beneficial outcome (NNTB) and the number needed to treat for an additional harmful outcome (NNTH) if statistically significant results were found. Continuous variables were analysed using mean differences and 95% confidence intervals.

Unit of analysis issues

The unit of analysis is the participating infant in individually randomised trials and the neonatal unit (or subunit) for cluster‐randomised trials; for cross‐over trials, see below.

Cluster‐randomised trials

When trials involved clustered randomisation, we anticipated that study investigators would have presented their results after appropriately controlling for clustering effects (robust standard errors or hierarchical linear models). If it was unclear whether a cluster‐randomised trial had used appropriate controls for clustering, study investigators would have been contacted for further information. When appropriate controls were not used, individual participant data would have been requested and re‐analysed using multi‐level models that control for clustering. Following this, effect sizes and standard errors would have been meta‐analysed in RevMan using the generic inverse method (Higgins 2020). If appropriate controls were not used and individual participant data were not available, statistical guidance would have been sought from the Cochrane Methods Group and from external experts as to which method should be applied to the published results, in attempting to control for clustering. If information was insufficient to control for clustering, outcome data would have been entered into Review Manager 5 using individuals as the unit of analysis, and sensitivity analysis would then have been used to assess potential bias from inadequately controlled clustered trials (Donner 2001).

Cross‐over trials

We planned to meta‐analyse cross‐over trials as recommended by Elbourne 2002. Ideally we would have used first period data from cross‐over trials and combined these data with data from parallel studies. Elbourne 2002 advises, “the results of two or more cross‐over trials might be combined, but with this pooled result kept separate from the data from parallel group trials.” However, we were unable to obtain such first period data for all included cross‐over studies. In addition, no parallel trials were identified; therefore, only cross‐over design trials were analysed. Elbourne 2002 recommends that use of the cross‐over design should be restricted to situations in which carryover of treatment effects across periods is unlikely. Thus, we planned to assess possible carryover effects of change in the intervention, that is, push and gravity gavage feeding, across study periods in each of the included trials (see Risk of bias in included studies). 

Dealing with missing data

We planned to contact the authors of all published studies if clarifications were required, or to request additional information. In the case of missing data, the number of participants for which data were missing was to be described in the results section and in the Characteristics of included studies table. Results for available participants were to be presented. We planned to discuss the implications of missing data in the review Discussion.

Assessment of heterogeneity

We planned to use Review Manager 5 to assess the heterogeneity of treatment effects between trials (RevMan 2020). We planned to use the two formal statistics described below.

1. Chi² test for statistical homogeneity (P < 0.1). Because this test has low power when the number of studies included in the meta‐analysis is small, we set probability at the 10% level of significance (Higgins 2020).

2. I² statistic, to ensure that pooling of data is valid. The impact of statistical heterogeneity will be quantified using this statistic, which describes the percentage of total variation across studies due to heterogeneity rather than to sampling error in Review Manager 5 (RevMan 2020). We planned to grade the degree of heterogeneity as follows: 0% to 30%, might not be important; 31% to 50%, moderate heterogeneity; 51% to 75%, substantial heterogeneity; 76% to 100%, considerable heterogeneity.

Assessment of reporting biases

We planned to assess reporting and publication bias by examining the degree of asymmetry of a funnel plot shown in Review Manager 5 (RevMan 2020).

Data synthesis

We planned to use the fixed‐effect model in Review Manager 5 for meta‐analysis (RevMan 2020).

Subgroup analysis and investigation of heterogeneity

1. Infants of very low birth weight (less than 1500 grams)

2. Infants receiving partial gavage feeding (more than one gavage tube per 24 hours) or all feeds via gavage tube

3. Infants receiving respiratory support (mechanical ventilation or continuous positive airway pressure) during the gavage feed

4. Positioning (supine, prone, lateral, head elevated)

Sensitivity analysis

When we identified substantial heterogeneity, we planned to conduct sensitivity analysis to determine if the findings were affected by inclusion of only those trials considered to have used adequate methods with low risk of bias (selection and performance bias). We reported results of sensitivity analyses for primary outcomes only.

The one identified study did not include the outcomes identified (Symon 1994).

Summary of findings and assessment of the certainty of the evidence

We used the GRADE approach, as outlined in the GRADE Handbook (Schünemann 2013), to assess the certainty of evidence for the following primary outcome: time taken to establish full gavage feeding (days) and feeding intolerance (number of episodes per day). This outcome was not reported in the included study. We were able to use the GRADE approach to assess the certainty of evidence for the following (clinically important) secondary outcomes.

• Respiratory rate (breaths per minute) at completion of feed.

• Respiratory rate (breaths per minute) 10 to 30 minutes after completion of feed.

• Heart rate (beats per minute) at completion of feed.

• Heart rate (beats per minute) 10 to 30 minutes after completion of feed.

Two review authors (JAD, JPF) independently assessed the certainty of evidence for each of the outcomes above. We considered evidence from RCTs as high certainty but downgraded the evidence one level for serious (or two levels for very serious) limitations based upon the following: design (risk of bias), consistency across studies, directness of evidence, precision of estimates, and presence of publication bias. We used the GRADEpro GDT 2021 Guideline Development Tool to create Table 1 to report the certainty of evidence.

The GRADE approach results in an assessment of the certainty of a body of evidence as meeting one of four grades.

1. High certainty: further research is very unlikely to change our confidence in the estimate of effect.

2. Moderate certainty: further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate.

3. Low certainty: further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate.

4. Very low certainty: we are very uncertain about the estimate.

Results

Description of studies

See Characteristics of included studies table.

Results of the search

The search for this updated review as of July 2020 yielded 2305 references. We screened 2092 studies after duplicates were removed. We reviewed 31 full‐text studies with only one observational cohort study ‐ Jabraeili 2018 ‐ comparing push verus gravity feeding. This study was one of the 30 studies excluded. After screening and review, we identified no new studies; for inclusion in this updated review (Figure 1). We identified no ongoing studies.

1.

Study flow diagram.

Included studies

Population

Symon 1994 studied infants who had a birth gestational age ranging from 24 to 32 weeks (mean 31.3 weeks). They had a corrected gestational age ranging from 26 to 37 weeks at the time of feeding. All had birth weight under 1750 grams, and all were under that weight when given the gravity/plunge feed. The average weight of babies was 1240 grams when feeds were given by plunge, and 1216 grams when feeds were given by gravity. Age ranged from 1 to 73 days (mean 18.6 days) for plunge feeds, and from 1 to 53 days (mean 21.55 days) for gravity feeds.

Interventions

The included study is a cross‐over trial (Symon 1994). Thirty‐one infants received 60 nasogastric feeds (30 plunge and 30 gravity). All feeds were given by the same researcher. No baby received more than three study feeds, and no baby received more than one study feed on any given day. All feeds were given while the infant was in a sleeping or resting state. A size 5 Vygon XRO feeding tube without an extension was used for all feeds.

Excluded studies

We excluded one study, which compared gavage feeds given by gravity with feeds given by syringe and injection over 30 minutes (Jabraeili 2018). The authors of this paper described the injection feeds as “push” feeds; however It is not clear if syringe/injection feeds were given by pump or manually by a nurse.

Risk of bias in included studies

Details of the methodological quality of the included trial ‐ Symon 1994 ‐ are given in the Characteristics of included studies table. The method of randomisation used in Symon 1994 was not identified. Correspondence with the primary author did not enable us to answer this question. There was no blinding of the intervention. Outcome measures were not blinded. All feeds were given by one researcher.

In the cross‐over study included in this review (Symon 1994), infants were exposed to more than one feeding method (push and gravity), and this may have confounded outcome measures. The primary author of Symon 1994 was not able to provide any information regarding length of time between treatments and thus possible carryover effects from one treatment to another (Figure 2).

2.

Risk of bias graph: review authors' judgements about each risk of bias item for the included study.

Allocation

This would appear to be a convenience sample. The method of identification of eligible infants is not fully described in the included study. The order of study feeds was randomly allocated, and the method of allocation was not described.

Blinding

This was an unblinded trial. Clinicians caring for the infant were aware of the method of tube feeding received by study infants. It would be difficult to blind this type of clinical intervention.

Incomplete outcome data

Completed data were provided for secondary outcomes for each infant in the study included in this review.

Selective reporting

The primary outcome of interest was not measured in the single study included in this review.

Other potential sources of bias

This is a small cross‐over study. Each infant received one feed by each method of tube feeding. Infants may have been exposed to both methods of gavage tube feeding before inclusion in the trial.

Effects of interventions

See: Table 1

See Table 1 ‐ push compared with gravity for bolus gavage feeding in preterm or low birth weight infants. We identified one trial with a total of 30 infants (Symon 1994).

Primary outcome

The included study did not measure either component of the pre‐specified primary outcome: time taken to establish full tube feeding (days) or feeding intolerance (Symon 1994).

Secondary outcomes

No data were available for any of the specified secondary outcomes; however, Symon 1994 compared gravity versus push gavage feeding for the following clinically important outcomes.

Effects of feeding method on respiratory rate (Outcomes 1.1 to 1.3)

There was no significant difference in respiratory rate at completion of feeds (mean difference (MD) 0.58, 95% confidence interval (CI) ‐5.97 to 7.13; 1 study, 31 participants; Analysis 1.1); at 10 minutes (MD 2.43, 95% CI ‐4.35 to 9.21; 1 study, 31 participants; Analysis 1.2); or at 10 to 30 minutes after completion of feeds (MD 3.10, 95% CI ‐3.43 to 9.63; 1 study, 31 participants; Analysis 1.3).

1.1. Analysis.

Comparison 1: Comparison 1. Push versus gravity bolus tube feeding, Outcome 1: Respiratory rate at completion of feed

1.2. Analysis.

Comparison 1: Comparison 1. Push versus gravity bolus tube feeding, Outcome 2: Respiratory rate 10 minutes after completion of feed

1.3. Analysis.

Comparison 1: Comparison 1. Push versus gravity bolus tube feeding, Outcome 3: Respiratory rate 10 to 30 minutes after completion of feed

Symon 1994 reported the statistical significance of the effects of feeding method on respiratory rate within each group rather than reporting the statistical difference between the two groups at each time period, as described above.

Effects of feeding method on heart rate (Outcomes 1.4 to 1.6)

There was no significant difference in heart rate at completion of feeds (MD ‐2.60, 95% CI ‐9.71 to 4.51; 1 study, 31 participants; Analysis 1.4); at 10 minutes (MD ‐2.40, 95% CI ‐9.59 to 4.79; 1 study, 31 participants; Analysis 1.5); or at 10 to 30 minutes after completion of feeds (MD ‐2.40, 95% CI ‐9.16 to 4.36; 1 study, 31 participants; Analysis 1.6).

1.4. Analysis.

Comparison 1: Comparison 1. Push versus gravity bolus tube feeding, Outcome 4: Heart rate at completion of feed

1.5. Analysis.

Comparison 1: Comparison 1. Push versus gravity bolus tube feeding, Outcome 5: Heart rate 10 minutes after completion of feed

1.6. Analysis.

Comparison 1: Comparison 1. Push versus gravity bolus tube feeding, Outcome 6: Heart rate 10 to 30 minutes after completion of feed

Symon 1994 reported the statistical significance of the effects of feeding method on heart rate within each group rather than reporting the statistical significance between the two groups at each time period, as described above.

Bradycardia

Symon 1994 reported bradycardia (not defined) during and immediately after gavage feeding. Four episodes of bradycardia were reported in each group.

Apnoea

Symon 1994 reported no episodes of apnoea (defined apnoea as complete cessation of breathing for longer than 15 seconds) during or after gavage feeding.

No studies examined time taken to establish full gavage feeding (days), feeding intolerance, apnoea during gavage feeding (defined as cessation of breathing for longer than 20 seconds or a shorter pause associated with bradycardia or cyanosis), apnoea (frequency of episodes within 30 minutes following gavage feeding), bradycardia during gavage feeding, bradycardia following gavage feeding, spontaneous episodes of oxygen desaturation during gavage feeding, spontaneous episodes of oxygen desaturation following gavage feeding, severe apnoea during gavage feeding, incidence of aspiration pneumonia, incidence of necrotising enterocolitis, days to regain birth weight, or length of hospital stay from admission to discharge.

Subgroup analysis

We were unable to conduct any of the planned subgroup analyses. 

1. Infants of very low birth weight (less than 1500 grams).

2. Infants receiving partial gavage feeding (more than one gavage tube per 24 hours) or all feeds via gavage tube.

3. Infants receiving respiratory support (mechanical ventilation or continuous positive airway pressure) during the gavage feed.

4. Positioning (supine, prone, lateral, head elevated).

Sensitivity analysis

We could not perform sensitivity analysis because only one trial is included in this review.

Discussion

One small quasi‐randomised controlled trial comparing push and gravity intermittent gavage feeding found a trend towards higher respiratory rate at 10 to 30 minutes following gavage feeds administered by the push method (Symon 1994). Conversely, Symon 1994 reported a significantly higher heart rate following gravity gavage feeding. It is important to note that Symon reported the statistical significance of the effects of feeding method on heart rate within each group. He did not compare the effects of feeding method on respiratory rate and heart rate between groups.

Confounding factors might affect the speed of a feed; these include diameter of the feeding tube, types of materials used in manufacture of the tube, and types of feed administered; when the gravity method is used, the height of the syringe above the baby will affect the speed of the feed.

We found little evidence to support the optimal speed for gavage feeding. Small, sick infants may be prone to respiratory instability during intermittent gavage feeding (Blondheim 1993). Blondheim showed that gravity feeds given over 15 to 20 minutes by gravity, when compared with continuous tube feeds, reduced adverse effects after feeding. Researchers did not measure the effects of push feeds. In the Symon study, feeds were not timed to last a specific number of minutes and seconds but were given in what the single observer felt was a 'safe manner'; however, there was little difference in the time taken to give feeds regardless of the method used (1.38 mL/kg/min for push feeds and 1.39 mL/kg/min for gravity feeds). The Winnipeg Regional Health Authority recommends an infusion rate of 2 mL per minute for bolus feeds. Further advice when a feed is administered via gravity is to position the syringe so that the feed infuses slowly (Winnipeg Regional Health Authority 2020). If the push method is used, the feed should be pushed slowly. Sankar recommends that feeding should take about 10 to 15 minutes to complete (Sankar 2008). Whilst these recommendations seem sensible, they are not evidence based.

The internal diameter, or bore, of the feeding tube will have an effect on the speed of the feed and may influence the choice of whether a bolus feed is given by push or by gravity. Ziemer favours push feeding when a small‐diameter feeding tube is used. She states that gravity is generally insufficient to administer an entire feeding, and some pressure must be exerted because of the small lumen of the feeding tube (Ziemer 1978). A laboratory study showed that using a 6‐fg tube without changing any other conditions (height above the infant or type of feed) resulted in faster feeding time than using a 5‐fg tube (Pagano 2010).

The height of the feeding tube above the infant is an important factor in determining the speed of a feed. Increasing the height will increase the force of gravity; as the height of a feeding is increased, the feed will be given at a faster rate (Pagano 2010). Little evidence is available regarding the optimum height of the tube when a bolus feed is given by gravity. Chin recommends that height should not exceed eight inches above the infant's head (Chinn 1971). Symon controlled for tube size and height above infants in his cross‐over study; all study feeds were given with a standard length 5‐fg feeding tube (Symon 1994).

The type of feed administered can have an effect on the speed of the feed. Pagano compared flow rates for artificial formula versus human breast milk and fortified human breast milk. She showed that human breast milk had the fastest flow rate. Milk with increased calorie content was the slowest. The type of milk administered in Symon 1994 is not described. Polyurethane feeding tubes compared to silicone tubes result in feeds given at a faster rate (Pagano 2010).

Despite the paucity of evidence, clinical practice guidelines have given clinicians recommendations regarding administering a bolus feeding only by gravity (Sankar 2008), or via push or gravity (Winnipeg Regional Health Authority 2020). This systematic review has not established which method of intermittent gavage feeding leads to better outcomes. Future studies should enrol preterm and low birth weight infants who require intermittent gavage feeding. Important outcomes would include those specified in our criteria for considering studies for this review.

Summary of main results

We found no studies that looked at time taken to establish full tube feeding (days) or feeding intolerance. Other outcomes ‐ respiratory rate (breaths per minute) or heart rate (beasts per minute) at completion of the gavage feed and 10 to 30 minutes after the gavage feed ‐ were assessed at very low certainty; therefore the evidence is very uncertain regarding effects of push versus gavage tube feeding on all other outcomes.

Overall completeness and applicability of evidence

The single included study was performed on preterm infants receiving bolus gavage feeds. The number of infants enrolled and the number of feeds tested were small. Evidence is insufficient to show whether use of push compared with gravity gavage feeding results in more rapid establishment of full gavage feeds without increasing adverse events in preterm or low birth weight infants, or both, who require intermittent bolus gavage feeding.

Quality of the evidence

Time taken to full gavage feeding and number of episodes of feeding intolerance between infants fed by push compared to gravity bolus gavage feeds were not reported; therefore evidence could not be judged. The certainty of evidence for respiratory or heart rate at completion of the feed and at 10 to 30 minutes after completion of the feed is graded as very low. We downgraded the evidence to low for outcomes reported mainly due to imprecision and risk of bias due to the unblinded nature of the intervention. In the only study reported in this review, infants received bolus gavage feeds both by push and by gravity at different feeds.

Potential biases in the review process

It is unlikely that the literature search applied to this review may have missed relevant trials; thus we are confident that this systematic review summarises all presently available evidence from randomised trials on push versus gravity for administration of bolus gavage feeds to preterm or low birth weight infants.

Agreements and disagreements with other studies or reviews

We are not aware of other reviews that address the same clinical question. We have described the characteristics of the only clinical trial that has been published.

Authors' conclusions

Implications for practice.

We do not have sufficient evidence to determine the effects of intermittent bolus gavage feeding for preterm and low birth weight infants. The single small study of 31 infants comparing effects of push versus gravity bolus gavage feeding did not report the primary outcome identified in this review. Evidence is very uncertain regarding effects of push compared with gravity gavage feeding resulting in more rapid establishment of full gavage feeds without increasing adverse events in preterm and low birth weight infants who receive intermittent bolus gavage feeding. In addition, the included study was too small to measure potential adverse events that can occur during gavage tube feeding, for example, episodes of oxygen desaturation, apnoea, or bradycardia.

Implications for research.

Intermittent bolus gavage feeding is a common practice in neonatal intensive care and special care baby nurseries. An RCT is needed to evaluate the benefits and harms of push versus gravity bolus gavage feeding in preterm infants. Infants should be stratified by gestational age at birth (above and below 32 weeks) or by birth weight (above and below 1500 grams). Subgroup analysis should include size of the enteral feeding tube, position of the infant, and speed at which the feed is delivered. The sample should be of sufficient size for evaluation of the primary outcome of this review (time to establish full tube feeds and feeding intolerance).

What's new

Date	Event	Description
30 July 2020	New search has been performed	The literature was searched on 30 July 2020. No new studies were identified. No ongoing trials were identified
30 July 2020	New citation required but conclusions have not changed	Our searches found no new studies. The conclusions of the review have not changed

History

Protocol first published: Issue 2, 2005
Review first published: Issue 11, 2012

Date	Event	Description
21 February 2013	Amended	Contact details were updated
10 January 2013	Amended	Contact details were updated
7 August 2008	Amended	Review was converted to new review format
16 May 2006	New citation required and conclusions have changed	Substantive amendments were made

Appendices

Appendix 1. 2020 search methods

The RCT filters have been created using Cochrane's highly sensitive search strategies for identifying randomised trials (Higgins 2020). The neonatal filters were created and tested by the Cochrane Neonatal Information Specialist.

CENTRAL via CRS Web

Date ranges: 01 January 2012 to 30 July 2020
Terms:
1 MESH DESCRIPTOR Enteral Nutrition EXPLODE ALL AND CENTRAL:TARGET
2 (((push* or gravity or gravitation or bolus or intermittent* or enteral* or nasogastric* or gastric*) and (feed* or fed or tube‐feed* or tube‐fed or gavage‐feed* or gavage‐fed or ((tube* or gavage*) and (feed* or fed)) or nutrition)) or (feeding method* or feeding strateg*)) AND CENTRAL:TARGET
3 #2 OR #1
4 MESH DESCRIPTOR Infant, Newborn EXPLODE ALL AND CENTRAL:TARGET
5 infant or infants or infant's or "infant s" or infantile or infancy or newborn* or "new born" or "new borns" or "newly born" or neonat* or baby* or babies or premature or prematures or prematurity or preterm or preterms or "pre term" or premies or "low birth weight" or "low birthweight" or VLBW or LBW or ELBW or NICU AND CENTRAL:TARGET
6 #5 OR #4 AND CENTRAL:TARGET
7 #6 AND #3
8 2012 TO 2020:YR AND CENTRAL:TARGET
9 #8 AND #7

MEDLINE via Ovid

Date ranges: 01 January 2012 to 30 July 2020
Terms:
1. exp Enteral Nutrition/
2. (((push* or gravity or gravitation or bolus or intermittent* or enteral* or nasogastric* or gastric*) and (feed* or fed or tube‐feed* or tube‐fed or gavage‐feed* or gavage‐fed or ((tube* or gavage*) and (feed* or fed)) or nutrition)) or (feeding method* or feeding strateg*)).mp.
3. 1 or 2
4. exp infant, newborn/
5. (newborn* or new born or new borns or newly born or baby* or babies or premature or prematurity or preterm or pre term or low birth weight or low birthweight or VLBW or LBW or infant or infants or 'infant s' or infant's or infantile or infancy or neonat*).ti,ab.
6. 4 or 5
7. randomized controlled trial.pt.
8. controlled clinical trial.pt.
9. randomized.ab.
10. placebo.ab.
11. drug therapy.fs.
12. randomly.ab.
13. trial.ab.
14. groups.ab.
15. or/7‐14
16. exp animals/ not humans.sh.
17. 15 not 16
18. 6 and 17
19. randomi?ed.ti,ab.
20. randomly.ti,ab.
21. trial.ti,ab.
22. groups.ti,ab.
23. ((single or doubl* or tripl* or treb*) and (blind* or mask*)).ti,ab.
24. placebo*.ti,ab.
25. 19 or 20 or 21 or 22 or 23 or 24
26. 5 and 25
27. limit 26 to yr="2018 ‐Current"
28. 18 or 27
29. 3 and 28
30. limit 29 to yr="2012 ‐Current"

CINAHL via EBSCOhost

Date ranges: 01 January 2012 to 30 July 2020
Terms:
(((push* or gravity or gravitation or bolus or intermittent* or enteral* or nasogastric* or gastric*) and (feed* or fed or tube‐feed* or tube‐fed or gavage‐feed* or gavage‐fed or ((tube* or gavage*) and (feed* or fed)) or nutrition)) or (feeding method* or feeding strateg*)) AND
(infant or infants or infant’s or infantile or infancy or newborn* or "new born" or "new borns" or "newly born" or neonat* or baby* or babies or premature or prematures or prematurity or preterm or preterms or "pre term" or premies or "low birth weight" or "low birthweight" or VLBW or LBW) AND
(randomized controlled trial OR controlled clinical trial OR randomized OR randomised OR placebo OR clinical trials as topic OR randomly OR trial OR PT clinical trial)
Limiters ‐ Published Date: 20120101‐20201231

ISRCTN

Date ranges: 01 January 2012 to 30 July 2020
Terms:
“push AND feed* AND ( Participant age range: Neonate )”
"push AND tube‐feeding AND ( Participant age range: Neonate )"
"push AND tube‐fed AND ( Participant age range: Neonate )"
"push AND gavage‐feeding AND ( Participant age range: Neonate )"
"push AND gavage‐fed AND ( Participant age range: Neonate )"
"gravity AND feed* AND ( Participant age range: Neonate )"
"gravity AND tube‐feeding AND ( Participant age range: Neonate )"
"gravity AND tube‐fed AND ( Participant age range: Neonate )"
"gravity AND gavage‐feeding AND ( Participant age range: Neonate )"
"gravity AND gavage‐fed AND ( Participant age range: Neonate )"

Australian New Zealand Clinical Trials Registry (ANZCTR)

Date ranges: 1 February 2020 to 30 July 2020
Terms: push AND feed*
push AND tube‐feed*
gravity AND feed*
gravity AND tube‐feed*

EU Clinical Trials Register (EU‐CTR)

Date ranges: 1 February 2020 to 30 July 2020
Terms: push AND feed*
push AND tube‐feed*
gravity AND feed*
gravity AND tube‐feed*

Clinical Trial Registry of India (CTRI)

Date ranges: 1 February 2020 to 30 July 2020
Terms: push AND feed*
push AND tube‐feed*
gravity AND feed*
gravity AND tube‐feed*

Appendix 2. Previous search methods

Electronic searches

We sought to locate randomised controlled and quasi‐randomised trials from the electronic databases Cochrane Central Register of Controlled Trials (CENTRAL; 2012 Issue 5), in the Cochrane Library; MEDLINE (from 1966 to May 2012), Embase (from 1980 to May 2012), and Cumulative Index to Nursing and Allied Health Literature (CINAHL) (from 1982 to May 2012) using the following subject headings (MeSH) and text words: [infant ‐newborn / OR infan*, or Neonat*, OR prematur* OR preterm OR low birth weight] AND [GORD, GERD, gastro‐oesophageal reflux, gastroesophageal reflux, infantile reflux, gastric regurgitation, gastric emptying, enteral feeding, enteral nutrition, feeding behaviour AND infant feeding, gavage feeding, intermittent feeding, bolus feeding, tube feeding, gastric feeding]. We did not apply language restrictions. Two review authors (JD, JF) independently performed electronic database searches.

Searching other resources

The search strategy also included communication with expert informants and searches of bibliographies of reviews and trials for references to other trials, abstracts, conferences, and symposia proceedings of the Perinatal Society of Australia and New Zealand and Pediatric Academic Societies (American Pediatric Society, Society for Pediatric Research, and European Society for Pediatric Research) from 1990 to 2011. If we identified any unpublished trial, we intended to contact the corresponding investigator to request information. We intended to consider unpublished studies and studies reported only as abstracts as eligible for the review if methods and data could be confirmed by the study author. We intended to contact the corresponding authors of identified RCTs for additional information about their studies if further data were required.

Appendix 3. ‘Risk of bias’ tool

1. Sequence generation (checking for possible selection bias). Was the allocation sequence adequately generated?

For each included study, we categorised the method used to generate the allocation sequence as:

1. low risk (any truly random process, e.g. random number table; computer random number generator);

2. high risk (any non‐random process, e.g. odd or even date of birth; hospital or clinic record number); or

3. unclear risk.

2. Allocation concealment (checking for possible selection bias). Was allocation adequately concealed?

For each included study, we categorised the method used to conceal the allocation sequence as:

1. low risk (e.g. telephone or central randomisation; consecutively numbered sealed opaque envelopes);

2. high risk (open random allocation; unsealed or non‐opaque envelopes, alternation; date of birth); or

3. unclear risk.

3. Blinding of participants and personnel (checking for possible performance bias). Was knowledge of the allocated intervention adequately prevented during the study?

For each included study, we categorised the methods used to blind study participants and personnel from knowledge of which intervention a participant received. Blinding was assessed separately for different outcomes or classes of outcomes. We categorised the methods as:

1. low risk, high risk, or unclear risk for participants; and

2. low risk, high risk, or unclear risk for personnel.

4. Blinding of outcome assessment (checking for possible detection bias). Was knowledge of the allocated intervention adequately prevented at the time of outcome assessment?

For each included study, we categorised the methods used to blind outcome assessment. Blinding was assessed separately for different outcomes or classes of outcomes. We categorised the methods as:

1. low risk for outcome assessors;

2. high risk for outcome assessors; or

3. unclear risk for outcome assessors.

5. Incomplete outcome data (checking for possible attrition bias through withdrawals, dropouts, protocol deviations). Were incomplete outcome data adequately addressed?

For each included study and for each outcome, we described the completeness of data including attrition and exclusions from the analysis. We noted whether attrition and exclusions were reported, numbers included in the analysis at each stage (compared with total randomised participants), reasons for attrition or exclusion when reported, and whether missing data were balanced across groups or were related to outcomes. When sufficient information was reported or supplied by the trial authors, we re‐included missing data in the analyses. We categorised the methods as:

1. low risk (< 20% missing data);

2. high risk (≥ 20% missing data); or

3. unclear risk.

6. Selective reporting bias. Are reports of the study free of the suggestion of selective outcome reporting?

For each included study, we described how we investigated the possibility of selective outcome reporting bias and what we found. For studies for which study protocols were published in advance, we compared pre‐specified outcomes versus outcomes eventually reported in the published results. If the study protocol was not published in advance, we contacted study authors to gain access to the study protocol. We assessed the methods as:

1. low risk (when it is clear that all of the study's pre‐specified outcomes and all expected outcomes of interest to the review have been reported);

2. high risk (when not all of the study's pre‐specified outcomes have been reported; one or more reported primary outcomes were not pre‐specified outcomes of interest and are reported incompletely and so cannot be used; study fails to include results of a key outcome that would have been expected to be been reported); or

3. unclear risk.

7. Other sources of bias. Was the study apparently free of other problems that could put it at high risk of bias?

For each included study, we described any important concerns we had about other possible sources of bias (e.g. whether there was a potential source of bias related to the specific study design, whether the trial was stopped early due to some data‐dependent process). We assessed whether each study was free of other problems that could put it at risk of bias as:

1. low risk;

2. high risk; or

3. unclear risk.

If needed, we explored the impact of the level of bias by undertaking sensitivity analyses.

Data and analyses

Comparison 1. Comparison 1. Push versus gravity bolus tube feeding.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1.1 Respiratory rate at completion of feed	1	59	Mean Difference (IV, Fixed, 95% CI)	0.58 [‐5.97, 7.13]
1.2 Respiratory rate 10 minutes after completion of feed	1	59	Mean Difference (IV, Fixed, 95% CI)	2.43 [‐4.35, 9.21]
1.3 Respiratory rate 10 to 30 minutes after completion of feed	1	59	Mean Difference (IV, Fixed, 95% CI)	3.10 [‐3.43, 9.63]
1.4 Heart rate at completion of feed	1	60	Mean Difference (IV, Fixed, 95% CI)	‐2.60 [‐9.71, 4.51]
1.5 Heart rate 10 minutes after completion of feed	1	60	Mean Difference (IV, Fixed, 95% CI)	‐2.40 [‐9.59, 4.79]
1.6 Heart rate 10 to 30 minutes after completion of feed	1	60	Mean Difference (IV, Fixed, 95% CI)	‐2.40 [‐9.16, 4.36]

Characteristics of studies

Characteristics of included studies [ordered by study ID]

Symon 1994.

Study characteristics
Methods	Randomised cross‐over study design 60 nasogastric feeds (20 by plunge, 30 by gravity) were given to 31 babies in the intensive care section of the study unit. No baby received more than 3 study feeds, and no baby received more than 1 study feed on any given day. All feeds were given by 1 researcher to obviate inter‐observer error, and all were given while the baby was in a sleeping or resting state
Participants	31 infants at 24 to 32 weeks' gestation (mean 28.5); at the time of feeding, corrected gestational age ranged from 26 to 37 weeks (mean 31.3) Age for plunge feeds ranged from 1 to 73 days (mean 18.6 days) and for gravity feeds from 1 to 53 days (mean 21.6 days) All participants had birth weight < 1750 grams. The average weight of babies was 1240 grams when feeds were given by plunge. and 1216 grams when feeds were given by gravity
Interventions	Push vs gravity gavage feeding
Outcomes	Respiratory rate before, during, and after feed Heart rate before, during, and after feed
Notes	No information provided (such as period between treatment changeover) regarding possible carryover effects from one treatment to another
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Insufficient information provided. Authors state (quote): “Each feed was allocated randomly to either the gravity or plunge method”
Allocation concealment (selection bias)	High risk	Clinical staff not blinded to intervention
Blinding of participants and personnel (performance bias) All outcomes	High risk	No blinding
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	No information provided
Incomplete outcome data (attrition bias) All outcomes	Low risk	All outcome data reported
Selective reporting (reporting bias)	Unclear risk	We were unable to obtain study protocol
Other bias	Unclear risk	No information provided (such as period between treatment changeovers) regarding possible carryover effects from one treatment to another

Characteristics of excluded studies [ordered by study ID]

Study	Reason for exclusion
Jabraeili 2018	Observational cohort study comparing push vs gravity feeding

Differences between protocol and review

We made the following changes to the published protocol (Dawson 2005).

1. As of July 2019, Cochrane Neonatal no longer searches Embase for its reviews. RCTs and controlled clinical trials (CCTs) from Embase are added to the Cochrane Central Register of Controlled Trials (CENTRAL) via a robust process (see How CENTRAL is created). Cochrane Neonatal has validated its searches to ensure that relevant Embase records are found while searching CENTRAL.

2. Also starting in July 2019, Cochrane Neonatal no longer searches for RCTs and CCTs on the following platforms: ClinicalTrials.gov or the World Health Organization’s International Clinical Trials Registry Platform (ICTRP), as records from both platforms are added to CENTRAL on a monthly basis (see How CENTRAL is created). Comprehensive search strategies are executed in CENTRAL to retrieve relevant records. The ISRCTN (at www.isrctn.com/, formerly Controlled‐trials.com) is searched separately.

3. For the 2020 update, we ran searches in the following databases: CENTRAL via CRS Web, MEDLINE via Ovid, and CINAHL via EBSCOhost. The search strategies are available in Appendix 1. Previous search methods are available in Appendix 2.

4. We added the methods and the plan for Summary of findings tables and GRADE recommendations, which were not included in the original protocol (Dawson 2005), nor in the previous publication of the review (Dawson 2012).

5. We changed the title from "Push versus gravity for intermittent bolus gavage tube feeding of premature and low birth weight infants" to "Push versus gravity for intermittent bolus gavage tube feeding of preterm and low birth weight infants."

Contributions of authors

JD (along with RS and JPF) revised the previous published review (Dawson 2012).

For this review update, JD and RS screened search outputs, assessed study eligibility, and extracted and synthesised data. JD and JPF assessed risk of bias across key domains. All review authors revised the final review update.

Sources of support

Internal sources

• Newborn Research Centre, The Royal Women's Hospital, Parkville, Melbourne, Australia

• Children's Hospital at Westmead, Australia

External sources

• NHMRC CRE Newborn Medicine, Australia

• Vermont Oxford Network, USA

  Cochrane Neonatal Reviews are produced with support from Vermont Oxford Network, a worldwide collaboration of health professionals dedicated to providing evidence‐based care of the highest quality for newborn infants and their families.

• The Gerber Foundation, USA

  Editorial support for this review, as part of a suite of preterm nutrition reviews, has been provided by a grant from The Gerber Foundation. The Gerber Foundation is a separately endowed, private, 501(c)(3) foundation not related in any way to Gerber Products Company.

Declarations of interest

JAD has no interest to declare.

RS has no interest to declare.

NB has no interest to declare.

JPF has no interest to declare.

Core editorial and administrative support for this review has been provided by a grant from The Gerber Foundation. The Gerber Foundation is a separately endowed, private foundation, independent from the Gerber Products Company. The grantor has no input on the content of the review nor on the editorial process (see Sources of support).

New search for studies and content updated (no change to conclusions)